K. Hashimoto et al., CHARACTERIZATION OF A CARTILAGE-DERIVED 66-KDA PROTEIN (RGD-CAP BETA-IG-H3) THAT BINDS TO COLLAGEN/, Biochimica et biophysica acta. Molecular cell research, 1355(3), 1997, pp. 303-314
A 66-kDa collagen fiber-associated protein (RGD-CAP) was isolated from
a fiber-rich fraction of pig cartilage by ultrafiltration and collage
n-affinity chromatography. Amino acid sequencing and cDNA cloning indi
cated that the RGD-CAP is identical or closely related to beta ig-h3 p
rotein which is induced in human adenocarcinoma cells by transforming
growth factor-beta (TGF-beta) (Skonier, J., Neubauer, M., Madisen, L.,
Bennett, K., Plowman, G.D., and Purchio, A.F. (1992) DNA Cell. Biol.
11, 511-522). The RGD-CAP, as well as beta ig-h3, has the RGD sequence
in the C-terminal region. The native RGD-CAP bound to type I, II, and
IV collagens even in the presence of 1 M NaCl. A recombinant preparat
ion of RGD-CAP expressed in Escherichia coli cells also bound to colla
gen but not to gelatin. The RGD-CAP mRNA was expressed in chondrocytes
throughout all stages, although the expression level was highest duri
ng the prehypertrophic stage. In addition, TGF-beta increased the RGD-
CAP mRNA level in chondrocyte cultures. Since RGD-CAP transcripts were
found in most tissues, this novel collagen-binding protein may play a
n important role in cell-collagen interactions in various tissues incl
uding developing cartilage.